Australia Narrows MH370 Pinger Location to ˜Some’ Kilometers

Australian Prime Minister Tony Abbott said he’s confident crews hunting for the missing Malaysian jet have narrowed down the location of its black box to “within some kilometers,” raising optimism the wreckage will be found.

“We are confident that we know the position of the black box flight recorder to within some kilometers,” Abbott said in Shanghai today. “Still, confidence in the approximate position of the black box is not the same as recovering wreckage from almost four and half kilometers beneath the sea or finally determining all that happened on that flight.”

Signals detected over the past six days helped investigators focus the search for the Malaysian Airline System Bhd. (MAS) plane in a smaller area of the southern Indian Ocean. Even so, it could take some days before submarine equipment can be deployed to visually identify any wreckage, said Angus Houston, who heads Australia’s Joint Agency Coordination Centre.

There has been no major breakthrough and an initial assessment of a signal picked up by an Australian P-3C Orion aircraft yesterday wasn’t related to an aircraft black box, Houston said in an e-mailed statement.

Underwater Vehicle

“A decision as to when to deploy the autonomous underwater vehicle will be made on advice from experts on board the Ocean Shield and could be some days away,” Houston said.

Pinpointing where and when to use the slow-moving sub is pivotal, according to Dukane Seacom, which makes the pingers.

Noise from the submersible would make it difficult to hear pulses at the same time, heightening the urgency to settle on an underwater patrol zone before the units’ batteries die.

“Everybody is trying not to jump to any conclusion that may lead to any further speculation,” said Scott Gustetter, chief executive officer of airline consultant Aspirion, in Sydney. “I think they would want to find it before they say this is what it is conclusively.”

Malaysian Air Flight 370 vanished en route to Beijing from Kuala Lumpur on March 8 with 239 people on board. With the hunt for the Boeing Co. (BA) 777-200ER running for 34 days, the beacons marking the jet’s cockpit-voice and flight-data recorders are at the edge of — if not beyond — the 30-day projected limit of their power packs.

Pinger Locator

“The more dots they can put on the map in terms of signals, then they can use the readings to narrow in,” Dukane Seacom President Anish Patel said in a phone interview from Sarasota, Florida, where the company is based.

That means waiting to deploy the Bluefin-21 unmanned submarine from the Ocean Shield, even though it’s tempting to do so now, Phoenix’s Gibson said in an interview. A team from Largo, Maryland-based Phoenix is aboard the Australian ship to run the towed pinger locator under contract for the U.S. Navy.

Bluefin-21 will scan the ocean bottom with soundwaves once the search zone is refined, according to the JACC. Sonar produces images identifying possible wreckage just as a sonogram shows human organs under the skin, enabling the sub to operate in an area where water depths exceeding about 4,500 meters (14,800 feet) keep the seabed in perpetual darkness.

False Leads

The possible signal detected by a sonobuoy from a Royal Australian Air Force AP-3C Orion patrol plane “has been determined as not related to an aircraft underwater locator beacon,” retired Air Chief Marshal Houston said in a statement yesterday.

False leads, dashed hopes and the failure to find any physical evidence have marked most of the mystery of Flight 370 so far. The Ocean Shield detected two signals on April 5 and two more on April 8.

In laboratory tests, batteries on the pingers have lasted as long as 42 days “at a much lower rate,” although after Day 40, the signal probably would be so weak as to not be worth the effort to find it, Dukane Seacom’s Patel said.

“You’d have to be right on top of it” to locate it after Day 40, he said. “This is all bonus time.”

A typical battery begins to fade after 35 days and loses “meaningful output” from 38 to 40 days, Patel said. The power declines to one-eighth to one-fourth of its normal level, he said.

Still Working

“I’m glad to hear they’re still picking up signals,” he said. “That means our batteries are still doing their thing.”

Pulses from the beacons may travel farther than two miles (3.2 kilometers) in “real-world” conditions compared with laboratory tests, Patel said. Underwater temperature inversion layers known as thermoclines also can bend or reflect sound waves.

“Because of the thermoclines, because of the way the ocean can channel the sound depending on currents and topology, you may get more travel,” Patel said. “A lot of different things factor into that.”

Both pingers on the two black boxes may be sending signals, and they could have ended up far apart underwater in the search zone, Patel said. That may explain why authorities haven’t further pinpointed where the signals are coming from. Pingers also can come loose in a crash, as occurred when Air France Flight 447 plunged into the Atlantic Ocean in 2009.

Probability Circle

Patel said Dukane Seacom, a unit of Hollywood, Florida-based Heico Corp. (HEI/A), has analyzed the findings from Ocean Shield and concluded that the signals were consistent with those from the company’s pingers.

“Narrowing the probability circle” of where a debris field lies is critical to an efficient underwater search, said John Fish, a principal of Bourne, Massachusetts-based American Underwater Search & Survey Ltd.

The four spots where the Phoenix team heard pinger sounds span a zone as long as 30 kilometers long on one side, according to the JACC. Even if that were tightened somewhat, a sonar-based hunt would take at least 20 days, said Fish, who has participated in numerous such searches.

If the Phoenix team can cut the zone to a square about 10 kilometers on a side, the search time would shrink to less than a week, Fish said in an interview.

Flight 370’s disappearance is now the longest in modern airline history, baffling authorities because contact was lost less than an hour into a routine trip as the jet headed north over the Gulf of Thailand. After vanishing from civilian radar, the wide-body craft doubled back, flew over Peninsular Malaysia and on into some of the world’s most remote waters.

While the motive behind that heading remains unknown, Flight 370 was deliberately steered south on a path ending in the Indian Ocean, Malaysian Prime Minister Najib Razak has said.